Anti-wheel-lock system



A D 5, v1939- c. r-. HlRsHFELD Er A1. 2,182,694

ANTI-WHEEL-LOCK SYSTEM Filed Feb. 21. 1955 4 sheets-sheet 1 5, 1939- c. F. HlRsHFELD ET AL 2,182,694

ANTI-WHEEL-Locx SYSTEM Filed Feb. 21. 19,35 4 Sheets- Sheet 2 ATTORNEY.

Dec. 5, 1939.

Filed Feb. 21`,. 1935 4 Shee'tSvSheet 3 ATTORNEY.

D 5 v1939- c. F. HIRSHFELD ET A1, 2,182,694

vANTI-wHEzaL-Locsk SYSTEM Filed Feb. 21, 1935 4 'Sheets-Sheet 4 (ondermeer:

ATTORNEY.

Patented Dec. 5, 1939 UNITED STATESr PATENT orrlceV ANTI-WHEEL-Locx SYSTEM of New York Application February 21, 1935, serial No. 7,581 13 claims. (ci. sos-21) This invention relates to automatic means operative during the application of braking pressures to wheels or drums connected to wheels to pre` vent locking of the wheels during linear travel of the vehicle.

A principal object of the invention is to employ a combination of electrical and mechanical means, for the above purpose, which will act to release the brakes in response to a tendency of a wheel to skid and before actual locking of the wheel occurs together with means controlled by and responsive to a time delay device to re-apply the brakes. The re-application of the brakes is therefore independent of wheel and track relation.

Another object is to provide means, as above described, which will act to-apply, release and reapply the brakes a successive number of times during a single manually controlled application of braking pressures to the wheels without materially decreasing the emciency of the brakes to stop the vehicle in a given linear travel.

In the case of a rail wheel of conventional size and weight it will be understood that when a wheel begins to slip prior to locking and the brakes are released whereby it becomes free to gain angular speed, an interval of time of the order of 116 to 1/5 of a second is necessary for this to happen because of the inertia of the wheel. It will also be understood that the closing of valves and building up of braking pressures for re-application of the brakes also necessarily consumes an vappreciable time so that if the train of mechaf nism were dependent for re-application upon a restoration of the wheel to a definite angular speed many feet of linear travel would be lost. It is therefore another object of this invention to provide release and re-application means operative in accord with a. time interval in such manner that functioning of the 'train of re-application means over-laps the period of releasing whereby total free releasing is attendant with an immediate response by the re-application means, the actual time interval being no longer than is theoretically and actually necessary.

A further object is to provide means for setting l the time delay mechanism, as desired, together with means convenient to the hand of an operator for selecting any one of a plurality of these predetermined settings.

A further object is to provide a release and reapplication means, as described, for each individual axle so that any three axles of a. conventional street car, for instance, are independent of a possible failure of brakes on any one axle.

A further object is to provide a number of other safety factors in contemplation of a trolley leaving the power line, derailing, etc., all of which will become hereinafter more fully apparent as reference is had to the accompanying drawings wherein my invention is illustrated, diagrammatically, by way of example, and in which- Figure 1 is a diagram illustrating the electrical control circuits, and the fluid braking mechamsm;

Fig. 2 is a vertical axial section of an inertia switch;

Figs. 3, 4 and 5 are detail sections taken respectively on lines 3-3, 4-4 and 5-5 of Figure 2;

Fig. 6 is an axial cross section illustrating the assembly of the inertia switch on a vehicle part;

Fig. '7 is a diagram of the device consolidated into a unit for controlling all brakes on a two truck rail car, and

Figs. 8 and 9 are diagrams for explanatory purposes.

With reference rst to Figure l, a core I having a winding W1 is connected in series with a resistor R1 and manual switch S1 to a source 2 of electrical energy, the winding W1 being grounded at 3 and the source 2 being grounded at 4. In parallel with the winding W1 is a condenser C1 and a line 5 extending from a point in advance of winding W1 to the ground 3 in order to short circuit the winding W1. In the line 5 is a switch S2 which, upon opening, interrupts the short circuit and as a. result, the voltage in the circuit is impressed upon the winding W1. The switch S2 is inertia operated as will be hereinafter more fully described.

Also connected to the electrical source 2 is a line 6, 6a, a resistance R4, a switch S3, and a line 1v grounded at 8. In the line l is a winding Wa having a core 9. An armature A1 opposite the corel l and subject to a spring I0 normally holds the switch S3 in an open position. A condenser C2 is interposedpetween the resistance R4 and the line l and in parallel with the switch Ss.

Also electrically associated with the core l isy a second winding W2 constantly energized by the line 6 which has one side grounded at 3 and the other side connected to the source 2 through a resistance Rz and a resistance R3 manually variable in magnitude by a suitable means such as a two throw switch S4, S5. The resistance R3 and switch S4, S5 provide for quick manual acljustment of control current to either one of two different predetermined values for a purpose which will be hereinafter pointed out.

The brake applying means as herein illustrated is of the pneumatic type but other systems may be equally well used. As illustrated, theinumeral II designates a wheel and I2 a brake shoe connected by a rod I3 to a piston' I4 in a fluid actuator cylinder I5. In the cylinder I5 is a brake take-off spring I6 for the shoe I2. Alconduit I1 connects the cylinder I5 into a casing I8 which has a restricted central portion I 9 provided with a valve seat thereby dividing the interior of the casing into two chambers, 2| and 22. The upper chamber 2| has an outlet port formed with a valve seat 23 which communicates through a conduit 24 with a manually controlled supply line 25 through which fluid pressure is transmitted to the piston I4 and the brake I2. The pressure of the fluid is controlled in any suitable manner by an operator. Slidably received in the chamber 22 is a piston 26 having a stem 21 extending past the valve seat 20. Integral with the stem 21 is a valve 28 for the seat 20. The stem 21 also carries a valve 29 for the valve seat 23 which is so spaced from the valve 28 that only one of said valves may be seated at one time. A spring 30l urges the valve 28 towards its seat 28 and likewise opposes the closing of the valve 29. The chamber 22 has an exhaust outlet 3|, and a feed conduit 32 from a casing 34. A ported wall 35 divides the interior of the casing 34 into two chambers 33 and 36. The port in the wall 35 constitutes a valve seat 38 for a valve seating toward the chamber 33. The upper wall of this chamber 33 is provided withan exhaust outlet l31 formed as a valve seat and alternate valves 38 and 48 connected by a stem 4I are provided for the seats 38 and 31 respectively. A spring 42 urges the valve 39 to a seating position and urges the valve 48 from its seat.

Integral with the valves and 39 isa rod 43 projecting outwardly of the casing 39 for pivotal engagement by an armature A: subject to the core 9, hereinbefore described.

In Figures '2 to` 6 inclusive a suitable inertia switch Sz is illustrated in detail. 'I'he switch comprises a housing 58 which is illustrated as being mounted on a transmission housing 5I containing an axle 52 which is journalled in twol wheels II of the vehicle.

It could be mounted in other suitable places as is evident to one skilled in the art. n.As now used, the combination is with hypoid gears with the propeller shaft leading into the frontend of the transmission housing and the pinion for my device coaxial with the kpropeller shaft and mounted at the rear of the housing. This pinion therefore functions just as though it were mounted directly on the end of the propeller shaft in case worm gearing instead of hypoid gearing were employed. Thus, a gear 53 on the axle 52 is in constant engagement with a pinion 54 on a' propeller shaft 55. Rotatably mounted in the housing 56 is a shaft 56 detachably connected by an element 56a to a gear 51 which constantly meshes with the gear 53 whereby the shaft 56 rotates in unison with the axle 52. Between the housing 5I and the housing 56 is a disk 58 supporting an oil seal 59 which excludes lubricating oils, contained in the transmission housing, from the switch housing. Rotatably supported on the shaft 56 by an anti-friction bearing 50 is a flanged drum 6I having a stud 62 radiating inwardly from the peripheral flange thereof. One end of a coil spring 63 is attached to the stud 62 and the other end is attached at 64 to the shaft 56.

A disk 56 of insulating material extends into and is keyed to the shaft 56 being clamped on the end of shaft 56 by a nut 65. The disk is recessed `at 61 to receive contact ngers 68 and alsoy at -by conducting elements 12 to a .ring conductor 13 --xedly mounted on and insulated from the shaft 56. Brushes 14 are slidably supported by stationi ary brackets 15 and resiliently urged by springs 16 into contact with the ring 13. Wire conductors 11 connect the brushes 14 to a stationary terminal post 18 to which the line 5, forming part of the diagram shown in Figure 1, is connected. The

drum 6I is grounded through its supporting bearing and the torsion spring 53.

In describing the operation of the device it will be assumed that the wheel II is rotating and that fluid under pressure is being supplied through the conduits 25 and 2,4, chamber 2| and conduit I1 to the cylinder I 5 to actuate the piston I4 and the brake shoe I2 into engagement with the wheel II. 'Ihe initial pressure in the line 25 may be initiated by a foot pedal, a hand lever or any system partially automatic subsequent to initiation by the operator of the vehicle. The term ma'nually controlled as hereinafter to be used is intended to include any means subject to the will of the operator. If the deceleration of Ythe wheel II is greater than can exist with normal braking so that the wheel begins to slip the inertia reaction of the drum 6I overcomes the torque of the spring 63 and rotates relative to the disk 66. Rotation of the drum 6I carries the Contactors away from the contact fingers 68 thereby interrupting the circuit from the line 5 to the ground.

Switch S2 is thus opened and it remains open until the spring 63 overcomes the inertia of the drum 6I thereby returning the contacts 1I to contact with the fingers 66.

Referring again to Figure 1, when the switch S2 is opened the full line voltage is impressed on the winding W1 and the resistance R1 in series so that current from the electrical source 2 flows through the resistance R1 and winding W1 to the ground 3, thus fully energizing the winding W1 and inducing a magnetic flux in the core I which attracts the armature A1 and closes the switch Sa instantaneously. 'I'he switch Sa is in series with the resistance R4 and the winding W3 so that when it is closed current from the electrical source 2 iiows through the line 6, resistance R4, switch S3 line 1 and the winding W: to the ground 8. A iiux is thus induced in the core 8 which attracts the armature Az, causing it to depress the rod 43 thereby seating the valve 40 and unseating the valve 39. Inasmuch as the chamber 36 is in constant communication with the conduit 25, through which' braking pressure is supplied, unseatlng of the valve 39 permits fluid under pressure to pass from the chamber 36 to the chamber 33, from which it is conducted by the conduit 32 to the chamberv 22. The pressure in the chamber 22 actuates the. piston 26 to unseat the valve 28 to seat the valve 29 since the piston has a greater bottom surface area than the top of the valve 28. The cylinder I5 and conduit I1 are thus opened to the exhaust port 3| whereby the fluid pressure in the cylinder I is rapidly dissipated and the brake is accordingly released.

Upon release of the brake the wheel II will cease its excessive angular deceleration and will thereafter resume normal rolling.l .The spring 63 will thereupon rotate the drum 6I relative to the disk i6 bringing the contactors 1I to re-engagement with the contact fingers 68, thus closing the switch S2 to short circuit the lwinding W1.

Stated briefly, the operation to this point is as follows: excessive deceleration of the wheel II results in an opening of the switch S2 and release of the braking pressure in the line Il. The distinction between slipping and locking, as herein used, is important. Slipping is the condition where the wheel has lost traction with the rail but is still turning and hence presenting a constantly changing area the condition where the wheel has completely ceased rotation and hence carries its portion of the weight of the vehicle on a small unchanging wheel tread area by skidding. Locking causes flat spots on the tread and hence it is this conditionl that applicants seek to avoid. The releasing, as hereinbefore described, will take place -in response to slipping and before locking'occurs. This may not be strictly true where the linear velocity of the wheel is very small when initial braking occurs, as in this case an actual locking may possibly occur before release, but it is true, with this exception.

When the switch S2 again closes and short circuits the winding W1 and, after a time interval determined by the inductance of W1 the resistance of W1 and the initial current of W1, the current through the winding W1 decays to zero, and with it the magneto motive force due to W1 inducing a flux in the core I. As the flux core I fades it reaches a point at which the spring IIJ moves the armature A1 away from the core I and coincidentally opens the switch S3. This absorbs a time interval many times longer than the time of closing for this reason: after the switch S3 is closed the air gap between the armature A1 and the core I is much smaller and it takes less magnetic flux to hold it closed than it did to start it closing. Therefore the current through W1 can be reduced considerably after S3 is closed before the spring III can pull it off the core I. When the inertia switch S2 is closed the current flowing around. in W1 can then flow around in a circle through W1 and S2 without having to pass through R1. Thus the reason for the delayed opening of S3 upon closing of S2 is that current owing through W1 does not have to pass through R1. This system as we have built it provides a time delay of approximately seven and a half ytimes as long to open S3 as to clo it. When the switch S3 is opened the current now through the winding W3 is interrupted and the armature A2 is pushed away from the demagnetized core 9 by the action of the spring 42.

At this stage of the operation the valve 39 is seated and the valve 4|! is unseated so that the fluid under pressure may exhaust from the chamber 22 through the conduit 32 and port 31. The spring 30 seats the valve 28 and directs the fluid under pressure from the conduit 24 to the cylinder I5 thereby re-applying the brake.

It will be understood from the foregoing that a loss of excessive angular deceleration is instantly followed by the beginning of the brake re-application cycle of operations and the instant of actual application is subject to control to the rail. Locking is by a denite and predetermined interval of time. This is the essence of my invention and is highly important for the following main reasons: first, the wheel II is heavy and hence its inertia can not be overcome without the lapse of time. If brake re-application should follow brake release in too rapid succession it is conceivable that the wheel might eventually lock. On the other hand, if re-application were delayed for any time interval after the wheel resumed rolling then the release device would lengthen the distance through which the vehicle must travel before the brakes can bring it to astop. It is thus essential to ideal operation that the factor time control the operation. With this system, the beginning of energization of the train resulting in re-application may be initiated before the Wheel actually begins to roll. In fact, applicants prefer this.

In order to provide flexibility of control, lt is desirable to be able to vary this time factor which must elapse before brake re-application. Up to this point the circuit 2, 6, S4, S5, R3, R2. W2, 3 has not been mentioned with regard to its effect on operation. This circuit may be suitably added for the purpose of giving a further control of the time delay element. This circuit is constantly energized since it is intended that the two-way switch S4, S5 be closed on one side or the other at all times. For instance, this switch may be placed convenient to the motorman or operator so that he can quickly change from a "dry rail setting to a slippery rail setting since it requires more time to get the Wheel I I rolling again after it has once started to slip on a slippery rail than it does on a dry rail. Bare-side resistor tubes R3 are suitable for shop adjustment of the contacts as indicated by the arrows.

The further control of the time after the switch S2 closes before the switch S3 opens is obtained by thus superposing on the magneto motive force of the winding W1 the magneto motive force of the winding W2 where the magneto motive force of W2 acts in the opposite direction to that of W1. When W1 is energized its magneto motive force is larger than that of W2 which remains energized continuously, and as the current dies in W1 there is a point where its magnete M"tive force drops down to that of W2 which makes it possible to reduce the net magneto motive force acting on the core I to zero before the current through W1 drops to zero. The time required to reduce the net magneto motive force in the core and hence the net flux is evidently subject to control by changing the constant value of the magneto motive force due to W2 which can easily be accomplished by changing the current through W2 by means of the rheostat Re. The effect of this circuit is seen in Figs. 8 and 9. In Fig. 8, the flux in the core I just after S2 'opens due to the winding W1 is indicated as W1 Flux and in Fig. 9 the flux in the core I .iust after S2 closes due to W1 is indicated as W1 flux. The ux in the core due to W2 is constant because W2 is constantly energized. The net flux in both instances is the difference between that induced by W1 and W2 from which it is seen that a slight change in the magnitude of the flux induced by W2 changes the time at which the net flux becomes zero much more effectively in closing (Fig. 9) than in opening (Fig. 8). This method of showing the effect of the bucking coil is not exhaustive but is correct to' show the effect graphically.

The condenso'rs C1 and C2 are used to reduce the intensity of the arcs when the switches'Sn and Sa, respectively, are opened.

In the interest of safety it will be noted that one terminal of each of the windings Wi, Wn and Wa, is grounded, andA that when there is no current flowing through Winding Wa the spring 42 and the uid pressure in the line 25 both act in the same direction to close the valve 39. This insures normal braking action in the event that the trolley pole leaves the wire rendering the entire circuit inoperative. Further, the switch S1 constitutes a safety precaution and may be opened by the motorman or operator in the event of the highly improbable condition where the armature A; is held closed by the constant current in the winding W2.

In Figure 7 the diagram illustrated in Figure 1 has been consolidated to equip each axle of a railV vehicle with an individual apparatus for controlling the brakes. For the purpose of understanding the apparatus shown in this view, attention is directed to the detailed description and illustration of YFigure 1, the same reference numerals being applied to this iigure as are employed in connection with Figure l. The vehicle is shown as having four axles, designated I, II,

III and IV and the respective circuits, individual to each axle, may be traced throughout the diagram by the reference characters of the axles which they control. For example a group of four adjustable resistances R3 are illustrated and the resistance I is in the circuit controlling the axle I, resistance II in the circuit controlling the axle II, resistance III in the circuit controlling axle III, and resistance IV in the circuit controlling axle IV. 'Ihe same procedure is followed 'throughout the entire diagram.

What we claim is:

1. In combination in a vehicle including wheels and an axle and manually controlled means for applying brakes thereto, automatic means for releasing said brakes subsequent to a slipping of said wheels, a time delay device, automatic means subject to said time delay device and responsive to the automatic releasing means for re-applying said brakes, and manual means for altering at will the time factor introduced by said time delay device.

2. In combination in a vehicle having wheels, axles and manually controlled brake applying means, an electric circuit having a Winding therein, a core for said winding, an armature -subject to actuation by said core upon energization, a second circuit including a switch connected to said armature for closing upon actuation of said armature by said core, an armature subject to said second circuit for. causing release and re-application of said brake upon energization and deenergization respectively of said circuits, and automatic means comprising an inertia switch responsive to rate of axle rotation for controlling energlz'ation and de-energization of said circuits.

3. In combination in a vehicle having wheels, axles and manually controlled brake applying means, an electric circuit having a winding therein, a core for said Winding, an armature subject to actuation by said core upon energization, a second circuit including a switchrconnected to said armature for closing upon actuation oi'said armature by said core, an armature subject to said second circuit for causing release and reapplication of said brake upon energization and de-energization respectively of said circuits. and

an inertia switch sensitive to initial slipping of one of said wheels for energizing said circuits and sensitive to the loss oi' excessive angular deceleration by said wheel for de-energizing said circuits.

4. In combination in a vehicle including wheels and an axle and manually controlled means for applying brakes thereto, automatic means for releasing said brakes in response to initial slipping of said wheels, said means comprising an electric circuit, armature means associated with the brake applying means and an inertia switch instantly sensitive to excessive angular deceleration or the wheels for energizing said circuit whereby said armature means is actuated to release said brake applying means, and means responsive to the loss of excessive deceleration by said wheels upon release of said brakes for re-applying said brakes.

5. In combination in a vehicle including wheels and an axle and manually controlled means for applying brakes thereto, automatic means for releasing said brakes in response to initial slipping of said wheels, said means comprising an electric circuit, armature means associated with the brake applying means, and an inertia switch instantly sensitive to excessive angular deceleration of the wheels for energizing said circuit whereby said armature means is actuated to release said brake applying means, said inertia switch de-energizlng said circuit upon loss of excessive angular deceleration by said wheels, means for actuating said armature to reestablish the application of said brakes upon de-energization oi said circuit, and a time' delay device including the inductance of a winding having a core magnetized by the current flow in said circuit for delaying for an appreciable period of time the actuation of saidF armature to re-establish brake application.

6. In combination in a vehicle including wheels. an axle and manually controllable means for applying brakes thereto, automatic means for releasing said brakes in response to initial slipping of one of said wheels, said means comprising two electric circuits, an inertia switch associated with the wheels for directly establishing a full current iiow through one of said circuits, a winding having a core therein also in the circuit controlled by said inertia switch, a switch in the other of said circuits adapted for actuation to closed position by said core upon energization of said circuit, a second winding having a core therein in said second circuit, an armature for said second core and means associated with said armature for releasing said brakes upon energization of said second circuit, and means for re-applying said brakes comprising said inertia switch which is adapted to interrupt -the current iiow thereby demagnetizing the core in said rst circuit, spring means for opening the switch in said second circuit whereby said second core is de-magnetized, and spring means for aiecting re-application of said brakes upon release of said armature by said second core.

7. In combination in a vehicle including wheels. an axle and manually controllable means for initially controlling the application of braking pressures to said Wheels, an electric circuit, a windinghaving a core in said circuit, armature means subject to said core for releasing said braking pressures upon energization of said circuit, inertia means sensitive to initial slipping oi' either of said wheels for energizing said circuit, and means for de-energizing said circuit and i'or re-applying said braking pressures subsequent to release thereof, said last named means comprising said inertia means and the inductance of said winding in opposing discontinuation of the current flow, a constantly energized bucking coil lll ' tive force capacity than said winding and a return spring attached to said armature.

8. The combinationas set forth in claim 'I together with rheostat means convenient to the operator of the vehicle for varying the current through said bucking coil. Y

9. The combination as set forth in claim 'Itogether with variable resistor means for controlling the intensity of current ow through said bucking coil, and a single pole multi-throw manual switch convenient to the operator of the vehicle for quickly selecting a given number of settings of said resistor means.

10. In combination in a vehicle including wheels, an axle and manually controllable means for controlling the application of braking pressures to said wheels, an electric circuit including in series a resistance and a winding having a core therein, an inertia switch and a ground for said circuit` in parallel with said winding and connected into said circuit between said resistance and said Winding, said switch being normally closed whereby said circuit is normally short circuited around said winding, a second circuit having a resistance, a second switch and a second winding in series therein, a second core for said second winding also having'a core therein, amature means connected to said second switch and subject to said first core for closing said circuit and energizing said second'winding upon opening of said normally closed switch to energize said first circuit, amature means subject to said second armature for releasing the braking` pressures against the vehicle wheels upon energization thereof, return springs connected 'toeach of said armatures for return to normal position thereof upon de-energization of said cores, said flrstswitch comprising an inertia device operative in response to the slipping of a wheel to open said first circuit, and a third circuit constantly energized and having a winding for said rst core having a magneto motive force impressed thereon in opposite direction to that of said rst winding whereby to aiect the time lof operation of said second armature following an actuating movement of said inertia controlled switch.

11. In combination with a veiiicie including wheels, an axle and means subject to the will of the vehicle operator for initially controlling the application of braking pressures to said wheels, a grounded electric circuit, a resistance and a coilhaving a core therein in series in said.

magnetic flux in circuit, an inertia switch sensitive to excessive rate of deceleration of one of the wheels connected intosaid circuit between said winding and said resistance in parallel with `said winding, a second circuit having a. resistanceand a switch therein,

armature means adjacent said core connected to said last named switch for closing said switch against a spring upon substantially full energization of said core by the opening of said inertia switch, means responsive to the energization of said second circuit for releasing the brake pressures against the resistance of a second spring, said inertia switch being adapted to close and thereby to short fcircuit said coil upon loss of ex'- cessive deceleration by said wheel whereby the said core fades, the spring of said armature and thespring of said spring-pressed means functioning to interrupt said second circuit and to restore said brake pressures respec tively as the flux in said core fades to an amount less than the force exerted by the spring opposing closing of said armature means.

l2. The combination of brakes. manual means for applying said brakes, mechanical means operative to release and reapply said brakes during application of said manual means, and an electrical circuit having armature means therein for actuating said mechanical means, said electrical circuit functioning instantaneously in response A to abnormal angular deceleraton of the device to which said brakes are applied to release said brakes, said circuit actuating said mechanical means to reapply said brakes upon loss of excessive deceleration by said device, said circuit having a time delay device therein whereby it lags in actuating said device to reapply said brakes.

13. The combination of vehicle brakes, manual means for applying said brakes, mechanical means operative to release and to reapply said brakes during application of said manual means, an electrical circuit having an armature therein for actuating said mechanical means, an inertia switch for short circuiting said circuit, said switch being adapted to open instantaneously in response to abnormal angular deceleration of one of the axles of the vehicle to energize said circuit thereby releasing said brakes, said switch closing immediately upon loss of excessive deceleration of said axle thereby interrupting said circuit, a time delay device operative immediately subsequent to the breaking of said circuit to de- 

